Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 21

Thread: PMC 3 silver clay pieces tarnishing really quickly - help!

  1. #11
    Join Date
    May 2014
    Posts
    63

    Default

    Hi, I am still confused.. The two ladies who's charms had tarnished have been re- polished by me and returned. They haven't worn them in the shower again and seem to be fine now.
    I had another customer today though, I only delivered her necklace last night and this morning it is tarnished. She hasn't showered in it but wore it over night.
    I can fully accept that silver tarnishes but this seems to be happening really quickly and it's worrying that it's happened to more than one customer

  2. #12
    Join Date
    Feb 2011
    Location
    Scotland
    Posts
    2,892

    Default

    This may seem a strange question but what age range are your customers. To me it still seems like an acid skin reaction and worn overnight may be excess sweating! Or did she put on hand cream, face cream, can't remember now how they were worn? Have you tried wearing it for a while to see what happens?

  3. #13
    Join Date
    Dec 2009
    Location
    London
    Posts
    147

    Default

    Hi Littlewhitefeathers,

    Sorry to hear about the issues you've been having with your metal clay products tarnishing. I've been working with PMC3 for a while now and have never come across this type of quick tarnishing before and I wear my rings and earrings made from PMC3 all day, every day. They are subjected to water, hand cream, perfume oils and London city pollution. Every couple of months I clean them in an ultrasonic cleaner and then barrel polish them - what I'm cleaning off is more like build-up of oil/dirt rather than tarnish.

    Some questions I have:

    * The items that have come back tarnished, were they all made from the same batch of PMC3?
    * Was each item made from a fresh packet of PMC3 or were they created at different times from a stored batch so?
    * If they were created from a stored batch, how and where did you store it?
    * Were the pieces bone dry before you fired them?
    * How did you fire the pieces (torch or kiln) and for how long?

    Issues with any of the above might be the cause, or something else that I haven't thought of

    Regards,

    V

  4. #14
    Join Date
    May 2014
    Posts
    63

    Default

    Thanks for the replies/questions..
    The age range is mostly 20s/30s..
    The latest piece I got back seems to be speckled black where as the other two that tarnished were more of a brown colour.

    They have all been made from different batches of pmc3. Some from new packets and some a mixture of packets deep isn't on how much I had left at the time.

    If made from a stored batch, the open packet of PMC had the clay wrapped tightly in cling film inside it then the packet was closed with a clip to stop air getting in.

    Fired them with a torch for 2 mins once glowing orange.

    I'm pretty sure they were all bone dry before firing, I've been sanding and finishing them once dry before firing and they all seemed dry.

    I tried wearing some of the charms today (they hang on a necklace against the chest) for a few hours and nothing happened.

    One thing I wondered was whether having gas appliances in the room I make the pieces might affect it at all. Usually, when I am making the pieces in my kitchen at the table, the gas oven and tumble dryer are off. But, they dry in the kitchen usually overnight and the applicants might be used in that time..

  5. #15
    Join Date
    Feb 2011
    Location
    Scotland
    Posts
    2,892

    Default

    Anything like that would burn out in the firing though. Speckled seems like perfume. I have a Dr friend who bought one of my pieces with a knitted insert. I saw her 3 weeks later puffed out with pride at her pendant while I was open mouthed! It was black striped, speckled you name it. She thought it was lovely I wanted to yank it off and clean it, god knows what she'd done. I only use PMC for accents but I've not had it tarnish anymore than anything else if left to the air, I have fired bits that have been floating around my junk tray for years and I don't think they have gone black.
    I have no idea what this could be but I'm sure they could easily polish them up with a silver cloth. I wonder if their other jewellery does the same?

  6. #16
    Join Date
    Dec 2009
    Location
    London
    Posts
    147

    Default

    OK.. so I did some research and found an interesting article on the Etsy Metal Clay Group called 'Tarnish Happens' (I can post links just yet), but if you search for 'Etsy Metal Clay Group Tarnish Happens' in your favourite search engine, you should be able to find it. Basically the article states that fine silver will tarnish at varying rates, depending on a number of factors like, the environment, climate and random stuff like wool, rubber bands, eggs, onions and people's body chemistry. Interestingly, the article suggests that silver jewellery should not be worn when applying make-up, cleaning or gardening or doing the dishes!

    I had another thought that possibly the tarnishing might be due to your firing methods, i.e. maybe your pieces aren't fully sintered, OR the butane fuel you're using contains contaminants.

    The article 'The Ultimate Silver Metal Clay Firing Guide - Cool Tools', is an interesting read and explains why 'long and hot' is important for full silver metal clay sintering (ignore the bit about alumina hydrate though - the dust it can create is a known respiratory irritant - vermiculite is safer).

    If you are creating a fair number of small pieces, maybe you could enquire if there's a kiln firing service near where you live, if you can't afford the outlay for a kiln.

    Hope some of this helps.

    Regards,

    V

  7. #17
    Join Date
    May 2014
    Posts
    63

    Default

    Thanks for the info!
    Not sure there's a kiln firing service here, I'm a bit out of the way..
    I may invest on a kiln in the future.
    What does sintering mean exactly? Would it help if I simply fired them with the torch for longer?

  8. #18
    Join Date
    Feb 2011
    Location
    Scotland
    Posts
    2,892

    Default

    I think I'll stick to what I do best , silver sheet and soldering!
    Last edited by CJ57; 13-06-2014 at 04:43 PM.

  9. #19
    Join Date
    Dec 2009
    Location
    London
    Posts
    147

    Default

    Sintering is described as 'the process of forming a solid mass of material by heat and/or pressure without melting it to the point of liquification'

    In the case of silver metal clay, sintering occurs when the tiny particles of silver are heated to a point just below the melting point of silver and they bond together to form solid metal.

    I think I mentioned in a previous post about 'The Ultimate Silver Metal Clay Firing Guide' by Mardel Rein on the Cool Tools site which gives a pretty good explanation of what the sintering process for silver metal clay is and how it is affected by time and temperature using experiments with PMC3 to illustrate.

    I kiln fire all my silver metal clay pieces regardless of size at 1650 deg F for a MINIUM of 2 hours which is the optimum schedule for silver metal clay sintering. Once the pieces are cooled, I work harden them with a hammer to compact and strengthen the metal structure even more. This results in a strong, durable piece of metal of assay quality. Torch firing does not give me this confidence as I have no idea what temperature my torch flame is at when I'm firing and also for how long I need to fire/hold for a particular weight/dimension of a piece for it to be fully sintered.

    I know it can be a tough decision, especially when you're just starting out using this 'magic putty' on the one hand, there is the daunting expense of buying a kiln but on the other hand, there is your own peace of mind and customer satisfaction. If there are any art colleges, in/around your area, I'd look into finding a kiln firing service as well.

  10. #20
    Join Date
    Aug 2012
    Location
    Oxon
    Posts
    394

    Default

    This article mentioned by vsilvered above explains sintering.
    Edit - the post above wasn't there when i typed this reply - honest!
    Last edited by trialuser; 13-06-2014 at 04:24 PM.

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •